The current in a wire varies with time according to the equation I(t) = 6 A + (4.8 A/s)t, where t is in seconds. How many coulombs of charge pass a cross section of the wire in the time period between t = 0.00 s and 3.5 s.

a)102.9 C
b)21 C
c)3.5 C
d)50.4 C
e)29.4 C

As part of an industrial process, air as an ideal gas at 10 bar, 400k expands at steady state through a valve to a pressure of 4 bar. the mass flow rate of air is 0.5 kg/s. the air then passes through a heat exchanger where it is cooled to a temperature of 295k with negligible change in pressure. the valve can be modeled as a throttling process, and kinetic and potential energy effects can be neglected. (a) for a control volume enclosing the valve and heat exchanger and enough of the local surroundings that the heat transfer occurs at the ambient temperature of 295 k, determine the rate of entropy production, in kw/k. (b) if the expansion valve were replaced by an adiabatic turbine operating isentropically, what would be the entropy production? compare the results of parts (a) and (b) and discuss.

Astone is thrown into a pond. what happens to the amplitude of the resulting waves as they get farther from the point where the stone hit the water? explain.

Awheel of mass 48 kg is lifted to a height of 0.8 m. how much gravitational potential energy is added to the wheel? acceleration due to gravity is g = 9.8 m/s2. a. 30.4 j b. 3.1 j c. 297.9 j d. 11,321 j